Debondable structure based on a solvent-borne pressure sensitive adhesive (psa)

Abstract

The present application is directed to a bonded structure comprising: a first substrate having an electrically conductive surface; and, a second substrate having an electrically conductive surface; wherein an electrochemically-debondable pressure sensitive adhesive film is disposed between the electrically conductive surfaces of the first and second substrates, said adhesive film being obtained by drying of a solvent-borne composition comprising, based on the weight of the composition: from 5 to 80 wt. % of a) at least one (meth)acrylate copolymer; from 0.1 to 30 wt. % of b) non-polymerizable electrolyte; and, from 10 to 90 wt. % of c) solvent.

1 : A bonded structure comprising:
 a first substrate having an electrically conductive surface; and,   a second substrate having an electrically conductive surface;   
       wherein an electrochemically-debondable, pressure sensitive adhesive film is disposed between the electrically conductive surfaces of the first and second substrates, said adhesive film being obtained by drying of a solvent-borne composition comprising, based on the weight of the composition:
 from 5 to 80 wt. % of a) at least one (meth)acrylate copolymer; 
 from 0.1 to 30 wt. % of b) non-polymerizable electrolyte; and, 
 from 10 to 90 wt. % of c) solvent. 
 
     
     
         2 : The bonded structure according to  claim 1 , wherein said solvent-borne composition comprises, based on the weight of the composition:
 from 15 to 75 wt. %, preferably from 30 to 70 wt. % of a) said at least one (meth)acrylate copolymer;   from 1 to 20 wt. %, preferably from 1 to 15 wt. % of b) said non-polymerizable electrolyte;   from 20 to 80 wt. %, preferably from 30 to 70 wt. % of c) solvent; and,   from 0 to 10 wt. %, preferably from 0 to 5 wt. % of d) solubilizer.   
     
     
         3 : The bonded structure according to  claim 1 , wherein a) said at least one (meth)acrylate copolymer is characterized by at least one of: a glass transition temperature (Tg) of from −30° C. to 60° C.; and, a weight average molecular weight of from 50000 to 500000 daltons. 
     
     
         4 : The bonded structure according to  claim 1 , wherein said at least one (meth)acrylate copolymer comprises, based on the total weight of monomers:
 from 35 to 95 wt. %, preferably from 50 to 90 wt. % and more preferably from 60 to 85 wt. % of a1) at least one (meth)acrylate monomer represented by Formula A1:
   H 2 C═CGCO 2 R 1    (A1)
 
    wherein: G is hydrogen, halogen or a C 1  alkyl group; and,
 R 1  is selected from: C 1 -C 30  alkyl; C 2 -C 30  heteroalkyl; C 3 -C 30  cycloalkyl; C 2 -C 8  heterocycloalkyl; C 2 -C 20  alkenyl; C 2 -C 12  alkynyl; C 6 -C 18  aryl; C 1 -C 9  heteroaryl; C 7 -C 18  alkaryl; and, C 7 -C 18  aralkyl; 
   from 5 to 65 wt. %, preferably from 10 to 50 wt. % and more preferably from 15 to 40 wt. % of a2) at least one (meth)acrylate monomer represented by Formula A2:
   H 2 C═CQCO 2 R 2    (A2)
 
    wherein: Q may be hydrogen, halogen or a C 1  alkyl group; and,
 R 2  is selected from: C 1 -C 18  hydroxyalkyl; and, C 3 -C 30  hydroxycycloalkyl. 
   
     
     
         5 : The bonded structure according to  claim 4 , wherein said at least one (meth)acrylate copolymer comprises, based on the total weight of monomers:
 from 35 to 95 wt. %, preferably from 50 to 90 wt. % and more preferably from 60 to 85 wt. % of al) at least one (meth)acrylate monomer represented by Formula A1:
   H 2 C═CGCO 2 R 1    (A1)
 
    wherein: G is hydrogen, halogen or a C 1  alkyl group; and,
 R 1  is selected from C 1 -C 12  alkyl and C 3 -C 12  cycloalkyl; 
   from 5 to 65 wt. %, preferably from 10 to 50 wt. % and more preferably from 15 to 40 wt. % of a2) at least one (meth)acrylate monomer represented by Formula A2:
   H 2 C═CQCO 2 R 2    (A2)
 
    wherein: Q may be hydrogen, halogen or a C 1  alkyl group; and,
 R 2  is selected from: C 1 -C 8  hydroxyalkyl; and, C 3 -C 12  hydroxycycloalkyl. 
   
     
     
         6 : The bonded structure according to  claim 4 , wherein a2) said at least one (meth)acrylate monomer represented by Formula A2 is selected from the group consisting of: 2-hydroxyethyl (meth)acrylate (HEMA); 2-hydroxypropyl (meth)acrylate; 3-hydroxypropyl (meth)acrylate; 3-hydroxybutyl (meth)acrylate; 4-hydroxybutyl (meth)acrylate; cyclohexanedimethanol mono-(meth)acrylate; 1,4-bis(hydroxymethyl)cyclohexane mono-(meth)acrylate; 1,4-dihydrocyclohexane mono-(meth)acrylate; and, octahydro-4,7-methano-1H-indene-dimethanol mono-(meth)acrylate. 
     
     
         7 : The bonded structure according to  claim 1 , wherein said non-polymerizable electrolyte is selected from the group consisting of 1-ethyl-3-methyl-1H-imidazol-3-um methanesulfonate, 1-ethyl-3-methyl-1H-imidazol-3-um methyl sulfate, 1-hexyl-3-methylimidazolium 2-(2-fluoroanilino)-pyridinate, 1-hexyl-3-methylimidazolium imide, 1-butyl-1-methyl-pyrrolidinium 2-(2-fluoroanilino)-pyridinate, 1-butyl-1-methyl-pyrrolidinium imide, trihexyl (tetradecyl) phospholium 2-(2-fluoroanilino)-pyridinate, cyclohexyltrimethylammonium bis (trifluoromethylsulfonyl) imide, di(2-hydroxyethyl) ammonium trifluoroacetate, N,N-dimethyl (2-hydroxyethyl) ammonium octanoate, methyltrioctylammonium bis (trifluoromethylsulfonyl) imide, N-ethyl-N-N-N-N-tetramethylguanidinium trifluoromethanesulfonate, guanidinium trifluoromethanesulfonate, 1-butyl-4-methylpyridinium bromide, 1-butyl-3-methylpyridinium tetrafluoroborate, 1-butyl-3-hydroxymethylpyridinium ethylsulfate, 1-butyl-1-methylpyrrolidinium bis (trifluoromethylsulfonyl) imide, 1-butyl-methylpyrrolidinium tris (pentafluoroethyl) trifluorophosphate, 1-ethyl-3-methyl imidazolium ethylsulfate, 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-ethyl-methylimidazolium bromide, 1-butyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium chloride, 1-octyl-3-methylimidazolium chloride, 1-methyl-3-octylimidazolium chloride, 1-propyl-3-methylimidazolium iodide, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-2,3-dimethylim idazolium tetrafluoroborate, 1-butyl-2,3-dimethylimidazolium hexafluorophosphate, 1-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium tetrafluoroborate, tetrabutylphosphonium tris (pentafluoroethyl) trifluorophosphate, trihexyl (tetradecyl) phosphonium tetrafluoroborate, 1-ethyl-3-methylimidazolium thiocyanate and mixtures thereof. 
     
     
         8 : The bonded structure according to  claim 7 , wherein said electrolyte is selected from the group consisting of 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methyl-1H-imidazol-3-um methanesulfonate, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, 1-ethyl-3-methyl-1H-imidazol-3-um methyl sulfate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium thiocyanate and mixtures thereof. 
     
     
         9 : The bonded structure according to  claim 1 , wherein said solvent comprises or consists of at least one compound selected from the group consisting of: diols having from 2 to 8 carbon atoms; and, esters having from 3 to 8 carbon atoms. 
     
     
         10 : The bonded structure according to  claim 1 , wherein said solvent-borne composition comprises a solubilizer in an amount up to 10 wt. % based on the weight of the composition, wherein said solubilizer is selected from the group consisting of polyoxy(C 2 -C 3 )alkylene glycols having an average molecular weight (Mw) of from 200 to 10000 g/mol. 
     
     
         11 : The bonded structure according to  claim 1 , wherein the first and second substrates are independently selected from the group consisting of: metallic films; metallic meshes or grids; deposited metal particles; conducting oxides; plastic or resinous substrates which are rendered conductive by virtue of conductive elements disposed therein; paper substrates which are rendered conductive by virtue of conductive elements disposed therein or thereon; and, woven or non-woven fabrics which are rendered conductive by virtue of conductive elements disposed therein or thereon. 
     
     
         12 : The bonded structure according to  claim 1 , wherein the electrically conductive surfaces of the first and second substrates are characterized by a surface energy of at least 50 dynes/cm, preferably at least 100 dynes/cm, more preferably at least 250 dynes/cm, as measured according to the method of ASTM D2578. 
     
     
         13 : A method of debonding said bonded structure as defined in  claim 1 , said method comprising the steps of:
   1 ) applying a voltage across both surfaces to form an anodic interface and a cathodic interface; and   2) debonding the surfaces.   
     
     
         14 : The method according to  claim 13 , wherein step i) of this method is preferably characterized by at least one of:
 an applied voltage of from 0.5 to 200 V; and,   the voltage being applied for a duration of from 1 second to 60 minutes.   
     
     
         15 : An electrochemically debondable pressure sensitive adhesive, said composition comprising, based on the weight of the composition:
 from 5 to 80 wt. % of a) at least one (meth)acrylate copolymer;   from 0.1 to 30 wt. % of b) non-polymerizable electrolyte; and,   from 10 to 90 wt. % of c) solvent.